不同巯基试剂修饰的CdTe量子点与BSA相互作用研究

修饰试剂对量子点的合成、性质具有重要的影响,但目前有关修饰试剂对量子点与蛋白质间相互作用的影响尚不清楚。采用紫外-可见吸收光谱、荧光光谱及红外光谱研究了3种巯基化合物(巯基乙酸,TGA;L-半胱氨酸,L-Cys;还原型谷胱甘肽,GSH)修饰的CdTe量子点与牛血清白蛋白(BSA)的相互作用。通过Stern-Volmer方程对数据进行了分析,得到了不同CdTe量子点与BSA相互作用过程的ΔHθ,ΔGθ和ΔSθ,并比较了CdTe量子点的不同修饰剂对BSA荧光猝灭的影响。研究结果表明,3种修饰试剂包覆的CdTe量子点与BSA的相互作用均为静态猝灭过程,猝灭常数KSV(L-Cys)KSV(TGA)≈KSV(GSH);TGA和L-Cys修饰的CdTe量子点与BSA的结合力主要为疏水作用力,而GSH修饰的量子点与其结合力既有氢键作用力又有疏水作用力;这些结果说明量子点与BSA的作用过程与量子点表面修饰试剂的类型有关。

Study on the Synchronous Interactions between Different ThioI-Capped CdTe Quantum Dots and BSA

The modifier of quantum dots plays an important role in synthesis and nature of quantum dots, however the effect on the interaction between quantum dots and protein is not very clear until up to now. In the present paper, the interactions of CdTe quantum dots with bovine serum album (BSA) were studied by spectroscopy methods including ultraviolet-visible absorption spectrometry (UV-Vis), fluorescence spectrometry (FL) and infrared spectrometry (IR). The CdTe quantum dots were modi-fied by three different thiol-complex including thioglycolic acid, L-cysteine and glutathione, i.e. thioglycolic acid capped CdTe quantum dots (CdTe~T), L-cysteine capped CdTe quantum dots (CdTe~L) and ghitathione capped CdTe quantum dots (CdTe~G) respectively. The quenching constant K_(SV) and corresponding thermodynamic parameters, such as enthalpy change (△H~θ), entro-py change (△S~θ), Gibbs free energy change (△G~θ), were calculated according to Stern-Volmer equations. The results showed that CdTe~T, CdTel. and CdTe~G all have a strong ability of quenching the fluorescence of bovine serum albumin, and the interac-tions of the three types of thiol-capped CdTe quantum dots with BSA were static quenching process. The quenching constant of K_(SV) (TGA) is similar to K_(SV) (GSH), which is much less than K_(SV) (L-Cys). The binding forces of CdTe~T and CdTe~L with the BSA were the main contributions from hydrophobic force according to the thermodynamic parameters (△H~θ＞0,△S~θ＞0 and △G~θ＜0), while the binding forces of CdTe~G with BSA were composed of both hydrogen bonding force and hydrophobic force accord-ing to the thermodynamic parameters(△H~θ＜0,△S~θ＞0 and △G~θ＜0. It was found that different functional group and molecular volume size of thiol surface modified reagent played an important role in the interactions between CdTe QDs and BSA.